Numerous Issues on 2000 Yamaha 115 TLRY (Making oil, High idle speed, surging RPMS)

[SBBCC333]

Purchased a boat with a 2000 115TLRY that was given a clean bill of health by a Yamaha dealer which has numerous problems.

1. Appears to be making oil. Thermostat was stuck open and we replaced.
2. Idles at 1100-1200
3. In high idle will go from 2000-3000 without any throttle input
4. Starting when warm goes immediatly to 2500 rpm then slowly comes down to 1100

Any suggestions on where to start? The yamaha dealer is across the country so I cant take it to them

[99yam40]

being a carbed motor, I would check compression to make sure that is good,
then check to see what timing is doing at idle when the RPM is moving around,

All I can think of is timing moving around or an air leak causing RPM to move

and then clean the carbs and follow the link and sync procedure in your service manual to make sure everything is set properly
( that includes the timing)

[SBBCC333]

being a carbed motor, I would check compression to make sure that is good,
then check to see what timing is doing at idle when the RPM is moving around,

All I can think of is timing moving around or an air leak causing RPM to move

and then clean the carbs and follow the link and sync procedure in your service manual to make sure everything is set properly
( that includes the timing)

This is a fuel injected motor.

[99yam40]

This is a fuel injected motor.

the 2000 115 TLRY shows up as carbed
Yamaha - Outboard - 2000 - 115HP - 115TLRY 2000 | Boats.net

[SBBCC333]

the 2000 115 TLRY shows up as carbed
Yamaha - Outboard - 2000 - 115HP - 115TLRY 2000 | Boats.net

Well I have a serious mystery. I just verified that the model number is F115TLRY on the serial number tag but my motor is fuel injected. Maybe the bracket was replaced at one point?

[99yam40]

the F115 is a 4 stroke and the 115 is a 2 stroke.
big difference in motors.
It is good idea to post the correct motor model # when asking about problems.
the 4 stroke probably has an Idle Air Control valve and lots of other things that a 2 stroke does not have

[SBBCC333]

the F115 is a 4 stroke and the 115 is a 2 stroke.
big difference in motors.
It is good idea to post the correct motor model # when asking about problems.
the 4 stroke probably has an Idle Air Control valve and lots of other things that a 2 stroke does not have

I understand the difference between 4 strokes and 2 strokes. I have an F115TLRY four stroke. My apologies for missing the "f". Now that we have this all cleared up any ideas? I took the IAC off yesterday and inspected everything. No signs over overheating and I can hear it resetting when turning engine off.

[99yam40]

compression and timing are still important.
Rail pressure it also very important.
the ECU thinks the rail pressure it in spec, but it does not monitor it.
VST pump and lift pump need to run when they should.
filters need to be clean,and VST needs to stay full
injectors need to fire when they should.
Cam timing belt needs to be in time too.
test what you can to eleminate what you can and then chase what is left